If you heart is age 50, I'd pay attention, if I were you. These are the numbers that doctors look at to gauge your heart health. The medical community didn't just make this stuff up. There's a medical connection between them and the heart.
I used to smoke. Your body is handling the abuse right now, but what will happen is that the effects will come to roost, and you will hit a wall. Your lungs are damaged (the cilia...they don't grow back). You have mild chronic pulmonary disorder; all smokers do. Your body as it ages will not handle it as well. That is true for any abuse, like too much booze, too much junk food, very overweight. All these things come home to roost in midlife. People start getting diabetes, high cholesterol, high bp, whatever. The metabolic syndrome from morbid obesity sets in, and the effects from smoking will start preventing a smoker from doing some things he used to do. With me, my lung capacity was enough that it was getting really difficult to carry bags of sand around my yard for gardening purposes. I'd get out of breath & tire out. Someone else may not have noticed, but I noticed, since I had a comparison that it used to be fairly easy. (I exercised regularly, so was in good shape.)